The present invention relates to moveable control fins for missiles carried on aircraft and more particularly to a system for locking the fin against aerodynamic loads and preventing the transmission of these loads through the drive train and upon receipt of a command signal activating a mechanical assembly which includes a force amplifier to ensure that the fin locking system is deactivated.
Flight control systems of many diverse types have been widely utilized. They generally include a control surface and in the case of a missile the control surface is typically a fin. Generally the control surface or fin is connected by a shaft adapted to be moveable for purposes of flight control. The fin shaft is generally connected through an output drive shaft that is rotated by connection through an appropriate drive train to a power source.
During flight before launch when the missile is positioned on the exterior of the aircraft the fin is subjected to high aerodynamic loading. This loading causes the fin to move in the direction of the load and in turn causes the fin shaft to rotate which rotation is transmitted through the drive train causing flutter and fatigue failures. Such is the case even when a brake mechanism is utilized in an attempt to stop the flutter rotation of the fin shaft or the output shaft.
As a result of this undesirable aerodynamic loading of the drive train, various attempts have been made to provide a lock which would eliminate the effect of aerodynamic loading. Examples of such locks designed particularly for utilization upon missiles or projectiles utilizing control fins are shown in U.S. Pat. Nos. 4,759;110; 5,409,185 and 5,505,408 and British Specification 560,931 accepted Apr. 27, 1944. Unfortunately, most locks for control surfaces such as fins on missiles have failed in numerous respects. For instance, some of the locks have been prone to sticking or otherwise failing to release upon command in a substantially frictionless fashion. Some locks have been prone to inadvertent unlatching due to vibration during normal operation. Other locking mechanisms are quite complex and include a large number of parts all of which must operate properly to avoid a malfunction. One system which overcomes many of the problems in the prior art is disclosed in application Ser. No. 09/419,544 filed Oct. 18, 1999 for Missile Fin Locking Mechanism, now U.S. Pat. No. 6,250,584, which is assigned to the assignee of the present application and is incorporated herein by reference. However, even that system from time to time experienced difficulty in retracting the locking pin from the fin immediately upon command.
The present invention is directed to a locking mechanism for use on a missile having a plurality of moveable control fins extending from an outer surface thereof, the locking mechanism includes a locking pin for each of the moveable control fins which is adapted to extend through the outer surface of the missile into an opening in the control fin to retain the control fin in a fixed position prior to launch is provided. A slide member which is moveable between a pin extend and a pin extract position with a plurality of links one coupling each of the pins to the slide member. When the slide member is in its pin extend position each of the links is positioned in a substantially dead center position. Means including a movable mass is provided for forcefully contacting the slide to initiate movement of the slide member away from its pin extend position. Spring means is provided at each locking pin for positively moving the slide member from its pin extend position to its pin retract position to remove each of the pins from the opening in its respective moveable control fin subsequently to contact of the movable mass with the slide member.